A known seat apparatus for a vehicle is disclosed in German Patent No. 100 14 823 C1. The disclosed seat apparatus for a vehicle includes a function of adjusting a height of a vehicle seat (a seat cushion). At an upper portion of an upper rail, a supporting member is provided to which each end of a pair of links for the adjustment of the height of the vehicle seat is rotatably connected. A parallel link system constituted by means of these links supports an upper structure of the vehicle seat such as a lower arm serving as a framework of the vehicle seat.
According to the seat apparatus disclosed in German Patent No. 100 14 823 C1, no reinforcement member is especially provided to the supporting member, which supports the link and the lower arm, and the like. Therefore, the supporting member may easily be deformed when it is applied with various loads. Further, because the lower arm, or the like, is supported via the link, if a large load is applied to the link because of a collision of the vehicle, for example, the link may be deformed caused by buckling and a height position of the vehicle seat may not be held any more.
In contrast, according to a seat apparatus disclosed in JP2000233671A, a highly rigid frame (21) having a partially closed cross section is connected to an upper portion of an upper rail having a U-shaped cross section opened downward. The frame (21) supports the lower arm, or the like. However, because the major portion of this frame in its cross section is in a closed state, a connecting mechanism and a connecting position of the frame relative to the upper rail may significantly be limited. Further, because of an increase of a cross sectional area of the frame due to its closed cross section, weight of the frame may be increased.
A need thus exists to provide a seat apparatus for a vehicle capable of improving strength for supporting the vehicle seat whereas restricting a limitation to an assembling property.